(1) Field of the Invention
The present invention relates to a direct type backlight module, especially for a backlight module that comprises a heat-insulating element for enhancing light emitting efficiency of the backlight module.
(2) Description of the Prior Art
The advantages of high pixels, low irradiation, high space flexibility, and low power consumption make the Liquid crystal displays (LCD) more and more popular in the display markets. In the LCD, the liquid crystal molecules can not luminescence themselves, and so a backlight light module is needed to provide light sources of the display.
Please refer to FIG. 1A, which shows a cross section view of a conventional liquid crystal panel 1 and a direct type backlight module 2 as the light source of the panel 1. The backlight module 2 comprises a back bezel 21, a light source 22, and a plurality of driving elements 23. The driving elements 23 comprise some electrical elements such as power crystals or transformers which may produce lot of heat while in operation, in which the heat thereto is a major heat source within the backlight module 2. Additionally, the light source 22 also produces heat while in emitting light. Two kinds of heats accumulate within the backlight module 2 and affect the quality of the backlight module 2. Therefore, a distance D between the back bezel 21 and the driving elements 23 is introduced so as to enable the interior hot air to convect around in the space 24 produced by the distance D.
Please refer to FIG. 1B, which is an enlarged view of a portion of FIG. 1A. While the LCD is erected, an air enters the space 24 from a down side thereof and moves upwards as shown. The convection process will make the heat accumulated around the electrical elements and hence make the air temperature increase gradually. The accumulation of heat may influence both the light source and electrical elements simultaneously, and may thus further affect the efficiency of the light source and the heat resistance of the electrical elements. Empirically, the heat may decrease the light emitting efficiency of the backlight module by about 10%.
Hence, how to reduce the effect of the generated heat upon the light emitting efficiency is definite an important issue in this industry.